1. Field of the Invention.
The invention in general relates to appliance timers, and more particularly to a dryer timer with a cylindrical cam and having a housing structure which enables the cam to be inserted in the housing in a direction radial to the axis of the cam.
2. Description of the Related Art.
Electromechanical timers in which a mechanical cam activates electrical switches in a programmed cycle to control the functions of appliances are well known. Most recent designs have included elongated electrical switch blades responsive to a cylindrical cam. The blades and cam are held in a housing. The housing structure is important since the blades and cam must be held firmly and within close tolerances in order to provide the desired programmed timing functions. Further the structure must be such that the relative position of the blades and cam are held over long periods of time since appliance timers are expected to operate reliably for five to ten years or longer. In addition, the housing must insulate switch blades from one another, which in dryer timers is a demanding requirement since the blades carry high power loads. U.S. Pat. No. 3,390,243 issued to G. Obermann; U.S. Pat. No. 3,727,015 issued to Elmo W. Voland, Harold T. Simmons and Pauker Kurt; U.S. Pat. No. 3,742,159 issued to William Ray Brown; U.S. Pat. No. 4,531,028 issued to Garry A. Stout and Donald L. Ray; and U.S. Pat. No. 4,538,037 issued to Daniel K. Amonett show typical appliance timer housings in the prior art. U.S. Pat. No. 3,390,243 and U.S. Pat. No. 4,531,028 disclose housings in which the blades are held in a terminal block assembly and the terminal block assembly and the cam are held between two plates. In such assemblies, the cam is axially placed on one plate and the terminal block holding the blades is usually attached to one plate after the cam is attached. These housings require the blades to be held in a terminal block which is separately manufactured. U.S. Pat. No. 3,742,159 shows a modular construction in which individual cams are inserted axially into separate wafers and the wafers are stacked to form the complete timer housing. This requires many more manufacturing steps than other housings. U.S. Pat. Nos. 3,727,015 and 4,538,037 show two different variations of a common timer housing which comprises a cup shaped portion in which the cam is inserted axially. The latter patent, U.S. Pat. No. 4,538,037, represents the current state-of-the-art in dryer timer housings. Each of the above two housings require the blades to be held in special jigs while the cam is inserted.